1. Field of the Invention
The present invention relates to acrylic ultraviolet light absorber and hindered amine light stabilizer compounds, method therefore and coating compositions containing the same, wherein the compounds include a carbamate functionality.
2. Discussion of the Prior Art
Curable coating compositions such as thermoset coatings are widely used in the coatings art. They are often used for topcoats in the automotive and industrial coatings industry. Color-plus-clear composite coatings are particularly useful as topcoats where exceptional gloss, depth of color, distinctness of image, or special metallic effects are desired. The automotive industry has made extensive use of these coatings for automotive body panels. Color-plus-clear composite coatings, however, require an extremely high degree of clarity in the clearcoat to achieve the desired visual effect. High-gloss coatings also require a low degree of visual aberrations at the surface of the coating in order to achieve the desired visual effect such as high distinctness of image (DOI).
In the field of automotive coatings, it has become an objective to obtain a clearcoat (i.e., the outermost automotive coating) that is resistant to being etched by environmental fallout. Environmental etching is manifested by pitting, water spotting or chemical spotting of the coating or any combination of these. Environmental etch resistance is desirable because it improves the appearance and useful life of the coating.
Environmental etch resistance can be measured by visual examination of the coating, or by a profilometer or by subjecting a coating on a test panel to a saline solution in a temperature gradient oven test. Environmental etch resistance is generally measured by visual examination by individuals skilled at examining finishes for the degree of environmental etch therein. Environmental etch resistance has become more important as the amount of acid rain, and other industrial fallout has increased. Currently, environmental etching of automotive finishes is generally greatest in the areas most greatly affected by industrial fallout.
The incorporation of the HALS or UVAs as free additions or as polymer or oligomer bound UVA or HALS into a coating composition generally improves resistance of the coating composition to degradation caused by ultraviolet light exposure. Binding the HALS or UVA to an oligomer or polymer stabilizes the HALS or UVA in a coating composition, prevents migration of the UVA or HALS into other coating layers and retains the UVA or HALS in the clearcoat, where it is needed.
A coating composition containing a carbamate functional resin has shown to be effective against environmental etch even without the addition of HALS and UVAs. The addition of free HALS and UvAs, (i.e. not polymer- or oligomer-bound), has effected little or no improvement in environmental etch resistance in the coatings containing carbamate functional resins. Unexpectedly, it has been shown that addition of the polymer- or oligomer-bound HALS or UVA to a carbamate containing coating provides improved environmental etch resistance of the cured film.